Fastener driving tool

ABSTRACT

A fastener driving tool comprising a drive track for guiding fasteners as they are driven, a driver slidable in said track and movable on a power stroke to drive fasteners and return stroke in the opposite direction, pusher means for feeding fasteners into the lower end of said drive track and movable between a forward position projecting into said drive track and a rearward position rearwardly retracted therefrom, initiating a power stroke of the driver, and means for retracting said pusher means from said drive track operable to prevent a power stroke of said driver until said pusher means is clear of said drive track.

United States Patent [72] Inventors Richard H. Doyle 3,099,837 8/1963 Heilman et a1 227/136 Mount Prospect; 3,172,124 3/1965 Kremiiler 227/8 Edward .I. Novak, Franklin Park, Ill. 3,232,511 2/1966 Crooks 227/130 32*?2 68 Primary Examiner-Granville Y. Custer, Jr.

At! Patented Feb. 1971 orney Mason, Ko1ehmamen,Rathburn and Wyss [73] Assignee Fastener Corporation Franklin Park, III. a corporation Illinois [54] FASTENER DRIVING TOOL 24 Claims 9 Drawing Figs ABbTIlhCT: A fastener dl'lVlIlg tool compr1s1ng a dr ve traek for guldlng fasteners as they are driven, a dl'lVCI' slidable in [52] US. Cl 227/8, Said track and movable on a power Stroke to drive fasteners 227/130, 227/136 and return stroke in the opposite direction, pusher means for [51] InLCl. B25c 1/04 f di fastemrs into the lower end of Said drive track and [50] Fleld of Search 227/8, 1 12, movablevbetween a forward positio'n projecting into Said drive 136 track and a rearward position rearwardly retracted therefrom, [561 References CM ifi' 'iai'lf 3121!? $321? 11153 513F815?tliT oiiriiil ifi UNITED STATES PATENTS prevent a power stroke of said driver until said pusher means 2,979,725 4/1961 WandeI et a1 227/13OX is clear of said drive track so Q 40 I00 I no lI2o $14 :08

'46 2b 4 I26 I22 30 18 n2 28 5 so 38 3a a as 0 96 8 36 1o 3 b i s2 22 D T 34b 1/ \es in In I G 661/34 60 64 69 as ado I38 PATENTEUFEBIBIQ?! V 3553438 sum 2 OF 4 FIG. 2

INVENTORS:

RICHARD H. DOYLE EDWARD J. NOVAK ATT'YS PATENTED FEBIBIBYI 3.563438 V sum 3 or 4 FIG?) I N VEN TORS;

RICHARD H. DOYLE EDWARD J. NOVAK FASTENER DRIVING TOOL The present invention relates to a new and improved power operated fastener driving tool and, more especially, to a tool of the type capable of driving relatively large fasteners, such as common nails and the like.

With the increased demand forpower driven fastener driving tools which are capable of handling the larger fasteners, such as 8d common nails and the like, it is desirable to provide feeding means for positively feeding or positioning successive nails into the drive track for driving by the reciprocating driver on a single power stroke. ne of the problems with these types of tools is that if the pusher means is not fully retracted from the drive track when a power stroke is commenced, the driver may engage the forward end portion of the pusher means while in the drive track and cause severe damage to the tool.

Therefore, it is an object of the invention to provide a new and improved power driven fastener driving tool.

It is also an object of the invention to provide a new and improved power driven fastener driving tool which eliminates the foregoing difficulties of prior tools of this type.

Another object of the present invention is to provide a new and improved fastener driving tool employing pusher means for feeding fasteners into the drive track movable between a forward position projecting into the drive track and a rearward position retracted therefrom, including means operable to positively retract the pusher means from the drive track before initiation of a power stroke of the driver is permitted.

Another object of the present invention is to provide a new and improved fastener driving tool of the character described employing means for disabling the tool from firing until the pusher has been fully retracted from and is clear of the drive I track.

Yet another object of the present invention is the provision of a new and improved fastener driving tool having means for automatically returning the driver after the completion of a power stroke and positively advancing another fastener into the drive track.

Yet another object of the present invention is the provision of a new and improved fastener driving tool of the character described having a safety valve means operable to prevent a drive stroke of the driver untilthe nosepiece of the tool is pressed against a workpiece and the pusher means has been fully retracted from the drive track.

Another object of the present invention is the provision of a new and improved fastener driving tool employing new and improved safety valve means operable to initiate the feeding of a new fastener into the drive track after each power stroke has been completed.

Yet another object of the present invention is the provision of a new and improved fastener driving too] employing means for automatically initiating a power stroke of the driver followed by a return stroke but preventing the power stroke from commencing until the pusher means has been positively retracted clear of the drive track.

Another object of the invention is toprovide a new and improved fastener driving tool of the character described including means for positively retracting the pusher from the drive track before a driving stroke is commenced and including plural means for operating or cycling the tool on successive power strokes.

Another object of the invention is to provide a new and improved fastener driving tool of the character described in the preceding object wherein the plural means includes a manually depressible trigger and presser foot means mounted adjacent the lower end of the drive track for direct engagement with the workpiece.

Still another object of the invention is the provision of a new and improved fastener driving tool having means operable to prevent the initiation of driving strokes when the supply of fasteners in the tool is exhausted.

These and other objects of the present invention are accom plished in one illustrative embodiment thereof comprising a power actuated fastener driving tool having a drive track and a driver slidably disposed therein for movement on a power stroke and a return stroke in an opposite direction. Pusher means are provided for feeding fasteners supplied on a carrier strip one at a time directly into the drive track. The pusher means is movable between a forward position, wherein the forward end portion projects into the drive track, and a rear ward or retracted position, wherein the pusher is completely clear of the drive track. Means are provided for initiating successive power and return strokes of the driver and control means are provided for positively retracting the pusher means from the drive track before a power stroke can commence. After each power stroke has been completed, the pusher means is operable to feed another fastener into position in the drive track and the tool is then ready for its next cycle of operation.

For a better understanding of the present invention, reference should be had to the following detailed description and the appended claims, taken in conjunction with the drawings, in which:

FIG. 1 is a cross-sectional view taken on a longitudinal plane of a new and improved fastener driving tool constructed in accordance with the features of the present invention;

FIG. 1a is a transverse cross-sectional view of the magazine feeding assembly of the tool taken substantially along line 1a of FIG. 1;

FIG. 2 is a cross-sectional view similar to F IG. l illustrating operative components of the tool in different operative positions wherein the driver is moving downwardly on a power stroke to drive a fastener positioned in the drive track;

FIG. 2a is a cross-sectional view similar to FIG. la and taken substantially along lines 2a of FIG. 2;

FIG. 3 is a cross-sectional view similar to FIG. 1 illustrating the operative components of the tool in another operative position, wherein the driver is in an upper or rest position after a return stroke has been completed;

FIG. 3a is a cross-sectional view similar to FIG. 1a taken substantially along the lines 30 of FIG. 3;

FIG. 4 is a cross-sectional view taken along a longitudinal center plane of another embodiment of a fastener driving too] constructed in accordance with the features of the invention;

FIG. 5 is a fragmentary cross-sectional view of the tool similar to FIG. 4 illustrating the operating components thereof as a drive stroke is proceeding; and

FIG. 6 is a fragmentary cross-sectional view of the too] similar to FIG. 5 illustrating the operative components thereof when the supply of fasteners is exhausted.

Referring now, more particularly, to the drawings and FIGS. 1, la, 2, 2a 3, and 3a, therein is illustrated one embodiment of a new and improved pneumatically operated fastener driving tool constructed in accordance with the features of the present invention and referred to generally by the reference numeral 10. The tool 10 includes a main body 12 formed with a hollow, rearwardly extending handle portion 14 which serves as a reservoir for holding a volume of compressed air for operation of the tool, the compressed air being supplied to the rear end of the handle portion through a suitable air line and disconnect fitting (not shown). The forward end of the handle portion 14 is integrally joined and in communication with a cylindrical head portion 16 extending generally transverse to the handle and projecting upwardly and downwardly thereof.

The head portion I6 is formed with a cylindrical bore I8 at the lower end, in which is slidably disposed the lower piston head 20 of a spoollike, reciprocably movable piston assembly 22. The piston assembly 22 includes an upper piston head 24 having a diameter slightly greater than the lower head 20, and a stem 26 of reduced diameter integrally interconnecting the upper and lower piston heads. An open, annular air space or piston chamber 28 is formed around the stem between the piston heads and is continuously supplied with compressed air from the handle 14 through a port 58 adjacent the upper end of the bore 18. The upper piston head 24 is slidable within a cylindrical insert 30 which is threaded externally at its lower end and seated within a threaded portion formed in the head portion 16 of the tool above the upper end of the lower cylindrical bore 18.

The internal diameter of the cylinder insert 30 is slightly larger than the diameter of the lower bore 18, and when pressurized fluid is present in the annular space or piston chamber 28 around the stem 26, a net resultant, upward force acts on the piston assembly 22 urging the assembly upwardly on a return stroke towards an upper or rest position, as shown in FIGS. 1 and 3, wherein the piston is at the top end of the head portion ofthe tool body.

The piston assembly 22 is connected at its lower end to a downwardly depending driver or drive rod 32, which is disposed for sliding movement within a cylindrical drive track 34 formed in a nosepiece 36 secured to the lower end of the head portion 16. The nosepiece 36 includes an integral, radially extending wall or flange 38 at the upper end which closes the lower end of the cylindrical bore 18 in the head portion 16, and the flange or wall is formed with a plurality of radially spaced holes 380 therein for venting the lower end of the bore 18 to the atmosphere, thereby maintaining atmospheric pressure on the underside of the lower piston head 20.

The upper end of the head portion 16 of the tool body is larger in internal diameter than the outer diameter of the cylinder insert 30, thereby forming an annular space or chamber 40 below the upper end of the cylinder insert. The chamber 40 is in open communication with the forward end of the hollow or handle portion 14 of the tool and is continuously supplied with compressed air therefrom. The upper end of the head is closed by a removable cap member 42 having an integrally formed, centrally disposed, upwardly extending projection 44 thereon.

In order to selectively open and close communication between the interior bore of the upper end of the cylinder insert 30 and the annular chamber or space 40, a slidable poppet valve member 46 is mounted for sliding movement in the large diameter, upper end portion of the head 16 for movement between the upper end of the cylinder insert and the lower surface ofthe cap member 42. The poppet valve 46 includes a circular, piston-type valve disc portion 48 with a resilient gasket 50 on the underside thereof adapted to seal the upper end of the cylinder insert 30 when the valve is closed (FIGS. 1 and 3), and includes a hollow stem 52 projecting upwardly from the disc portion and slidable within a cylindrical bore 44a formed in the upper projection 44 on the cap member 42. The bore 44a is normally vented to the atmosphere through a laterally extending exhaust port 44b when the poppet valve 46 is closed, and when the valve is opened (FIG. 2) the stem 52 moves upwardly in the bore and closes the port, thereby sealing the upper end ofthe tool from the atmosphere.

The large diameter, upper end portion of the head 16 of the tool body forms an annular valve chamber 54 in which the flange or disc portion 48 of the poppet valve is slidable between an upper or open position adjacent the lower surface of the cap member 42 and a closed position, spaced downwardly thereof, closing off the upper end of the cylinder insert 30. When the valve chamber is supplied with pressurized fluid from the handle 14, the fluid pressure acting on the upper surface of the valve disc portion 48 causes the pop pet valve 46 to move downwardly to the closed position against the upper end of the cylinder insert 30.

In order to tire the tool and thereby cause the piston assembly 22 and driver 32 to move rapidly downward on a power stroke, the fluid in the poppet valve chamber 54 is exhausted to the atmosphere by means to be described hereinafter and, when this occurs, air pressure within the annular chamber 40 beneath the outer peripheral portion of the valve disc portion 48 acts upwardly on the valve, forcing it upwardly to the open position. The upper end of the cylinder insert 30 is thus opened and in direct communication with the pressurized fluid in the annular space 40, and this fluid rapidly flows into the upper end of the cylinder insert above the piston head 24, causing the piston assembly 22 to be driven rapidly downwardly on a power stroke. When a power stroke is thus initiated by evacuation of the poppet valve chamber 54 above the valve disc portion 48, the stem portion 52 seals off the lateral vent port 44a in the cap projection 44 so that pressurized fluid in the upper end of the tool cannot escape to the atmosphere, and thus maximum fluid pressure is available for driving the piston assembly 22 rapidly downward on a power stroke.

In order to cushion or dampen the shock of the piston assembly 22 and driver 32 at the end of the power stroke, a resilient, annular cushion member 56 is mounted on the upper surface of the flange or wall portion 38 of the nosepiece 6. The resilient cushion 56 includes a plurality of vent holes 56a in alignment with the ports 38a in the flange 38 to continuously vent the lower end of the bore 18 beneath the lower piston head to the atmosphere.

After a power stroke of the piston assembly 22 and driver 32 has been completed, the poppet valve chamber 54 is again pressurized and the poppet valve 46 returns downwardly to the closed position, sealing off the upper end of the cylinder insert 30. When this occurs, the' valve stem 52 moves downwardly and opens the exhaust port 44b in the cap projection 44 and the fluid in the upper end portion of the cylinder insert 30 above the upper piston head 24 is vented to the atmosphere through the hollow bore in the stem portion 52 and the exhaust port 44b.

The annular piston chamber 28 around the stem 26 between the upper and lower piston heads, is continuously supplied with pressurized fluid from the handle reservoir portion 14 through the port 58 formed in the wall portion of the head 16 immediately below the cylinder insert 30 and, because the upper piston head 24 is slightly larger in diameter than the lower piston head 20, the pressurized fluid in the piston chamber 28 acts on the piston assembly 22 with a net resultant upward force which causes the piston assembly to move upward on a return stroke. When the piston assembly 22 is returned to the upper end of the cylinder, the upper surface of the piston head 24 engages the lower surface of the gasket 50 on the poppet valve flange 48, limiting further upward travel of the piston assembly, and the tool is now ready for another cycle of operation as described.

In accordance with the present invention, the tool 10 is adapted to drive relatively large roundhead nails or fasteners 60 which are supplied from a continuous flexible carrier strip 62 and fed into the drive track 34 beneath the lower end of the driver 32 when the piston assembly 22 is in its upper or rest position. A carrier strip of the type disclosed in US. Pat. application Ser. No. 637,510, filed May l0, I967, now US. Pat. No. 3,438,487, issued Apr. I5, 1969 is suitable for holding the nails.

The drive track 34 is provided with a lateral, rearwardly facing feed opening 34a (FIG. 3) to accommodate the nails 60 and the carrier strip 62 which are fed forwardly into the drive track from a rearwardly extending magazine 64, and a forwardly facing exit opening 34b is provided on the forward wall of the drive track opposite the feed opening 34a to accommodate the carrier strip moving out of the drive track after each nail has been driven. The magazine 64 includes a pair of spaced apart, parallel sidewalls 66 and 68 for guiding the nails toward the drive track, and longitudinal grooves are formed on the facing inside surfaces thereof as at 66a for supporting the round heads of the nails. Top and bottom walls 67 and 69 are provided for completing the magazine enclosure, and the nails on the carrier strip are thus held and guided by the magazine during forward movement into the drive track.

In accordance with the present invention, the driving tool 10 includes a fastener feeding assembly 70 which is adapted to feed the nails 60, one at a time, from the magazine 64 into the drive track 34 in synchronism with the operation of the driver 32. The feeding assembly 70 is operatively interconnected with a manual trigger valve assembly 72 which controls the (iring of the tool and a safety valve assembly 74 associated therewith for preventing a firing stroke of the tool unless the lower end of the nosepiece 36 is positioned against a workpiece.

The magazine feeding assembly 70 includes a piston member 76 which is disposed for sliding movement within a cylinder or bore 78 formed in the tool body 12 and extending axially parallel with the longitudinal axis of the magazine 64. The bore 78 is closed at its forward end and is open to the atmosphere at the rearward end, and the feeder piston member 76 includes an elongated stem 80 coaxial with the bore having an enlarged handle portion or knob 82 at the outer end to facilitate manual movement of the piston. The piston 76 is movable between a rearward position, as shown in FIG. 2, a forward position, as shown in FIG. 1 and a full forward or shutoff position as shown in FIG. 3, in synchronism with the operating cycle of the piston assembly 22 and driver 32. The outer end portion of the stem 80 externally of the bore 78 is connected to a downwardly and forwardly extending reciprocal feeder member 84 having a pivot pin 86 adjacent the forward end thereof and laterally offset from the longitudinal axis of the magazine 64. A nail engaging pawl or finger 88 is pivotally mounted on the pin 86 and is biased inwardly towards the central, longitudinal axis of the magazine 64 between the opposite sidewalls 66 and 68 by means of a spring 90, mounted on the pin 86, as best shown in FIGS. la, 2a, and 3a. The forward end or tip of the pawl or finger 88 is movable inwardly into the interior of the magazine 64 between the sidewalls and directly into the drive track 34 through a slot or opening 66b formed in the sidewall 66 and an adjacent opening 34c formed in the drive track adjacent the rearward lateral feed opening 340 thereof. The forward end of the finger is adapted to directly engage the shanks of the nails 60, as shown in FIG. 2a, and advance the nails forwardly into a centered position in the drive track (FIG. la) upon forward movement of a feeding stroke of the feeder member 84 from the position of FIG. 2 to the position of FIG. 1. The spring 90 urges the finger 88 in a counterclockwise direction about the pin 86 so that the forward end or tip of the finger is biased against the inside surface of the opposite sidewall 68 of the magazine and this insures that a fastener or nail 60 is positively engaged by the forward end surface of the finger upon movement in a forward direction. As the finger 88 is moved rearwardly of the drive track on a rearward or return stroke of the member 84, engagement between the nail 60 in the magazine next adjacent the drive track cams the finger outwardly or in a clockwise direction, until the tip of the finger moves to the rear of the nail, and at this time the spring 90 is then free to urge the finger inwardly toward the opposite sidewall 68 so that on the next forward or feed stroke of the finger 88 the nail is positively engaged by the finger and is fed into a centered position in the drive track for driving, as shown in FIG. 1a. In the forward position (FIG. 1), the pawl finger 88 projects directly into the drive track beneath the head of the nail, and further forward travel is limited by the nail itself.

In order to prevent rearward movement of the nails 60 and carrier strip 62, when the pawl or finger 88 is moved on a rearward or return stroke, the sidewall 68 is provided with a slot 68a therein for accommodating a spring latching member 92 which projects into the guideway and resiliently engages longitudinally spaced slots or openings in the web portion of the carrier strip at a position spaced rearwardly of the drive track. The spring member 92 normally prevents rearward movement of the nails in the magazine unless sufficient force is used to overcome the spring latch 92 when it is desired to rearwardly retract the nails from the magazine. On each forward or feed stroke of the feed member 84, the nail 60, engaged by the forward tip of the finger 88, is fed into centered position in the drive track ready to be driven. Before the driver 32 is activated on a downward power stroke, the feed finger 88 is retracted rearwardly until the forward tip is clear of the drive track and, after completion of the power stroke and during or after return of the driver to the rest position, another feed stroke of the feed member 84 is initiated, carrying the next nail into a centered position in the drive track. This cycle is re peated until all of the nails contained in the magazine 64 have been driven. After the last remaining nail has been driven, the feed finger 88 is no longer restrained by the nail in the drive track and moves to a full forward position shown in FIG. 3. When the feeder member 84 is in full forward position, a power stroke cannot be initiated, as will be described hereinafter, until a new supply of nails 60 has been loaded into the magazine and the leading nail has been advanced into position for driving centered in the drive track, as shown in FIG. I. By grasping the knob 82, manual rearward retraction of feed member 84 clears the finger 88 from the drive track and permits the insertion of a new supply of nails into the magazine and, after insertion of the nails, the knob 82 is released and the spring 98 moves the member 84 forwardly carrying the first or leading nail in the strip into the drive track.

The feeder piston 76 is formed with a pair of axially spaced piston heads 94 and 96 mounted on or integrally formed with the small diameter, elongated stem and is biased forwardly in the bore or cylinder 78 by means of a spring 98 having a forward end bearing on the rearward face of the piston portion 96. The outer end of the spring is seated against an inwardly extending, annular flange 78a adjacent the open rearward end of the bore 78.

As previously described, the poppet valve 46 initiates a driving stroke of the piston assembly 22 and driver 32 and the poppet valve is moved from the closed to the open position by exhausting of air pressure from the valve chamber 54 above the valve disc or flange 48. In order to provide a path for exhausting this valve fluid to the atmosphere, the cap member 42 is formed with a passage 42a therein which is in communication at its outer end with a vertical, drilled passage 100 formed in the upper end portion of the head of the tool body. The lower end of the passage 100 is connected to a tubular conduit 102 extending transversely across the hollow handle portion 14 and connected at its lower end to a short, vertical passage 104 formed inthe tool body 12 beneath the handle. The passage 104 is connected with a rearwardly extending passage 106 which is in communication at its rearward end with a trigger valve chamber 108 of the trigger valve assembly 72. Intermediate the ends of the passage 106 of the tool body is provided a vertical bore or passage 1.10 of the safety valve assembly 74, and mounted in the passage for vertical sliding movement therein is a safety valve member 112 having a lower end extended downwardly from the lower open end of the bore 110. The trigger valve chamber 108 is in communication with the source of compressed air in the tool handle 14 through a small passage or port 114 in communication with the upper end thereof, and a ball valve 116 is loosely mounted in the chamber for movement between the upper and lower ends of the chamber. O-ring type valve seats 118 and 120 are mounted in the valve chamber 108 at the upper and lower ends, respectively, for cooperating seating engagement with the ball valve 116 in either its upper or lower position. The lower end of the trigger valve chamber 108 is in communication with a downwardly extending, drilled passage 122 open to the atmosphere at its lower end and a manual operator 124 is slidably disposed within the passage to activate the ball 116 and to prevent the escape of fluid from the valve chamber to the atmosphere through the lower end of the passage. The operator 124 includes a reduced diameter, upper pin portion 126 adapted to directly engage the ball I16 and move it off the lower O-ring 120, thereby opening communication between the passage 106 and the passage 122 through the valve chamber 108. When the valve operator 124 is moved from the position of FIG. 1 to the position of FIG. 2, the ball 116 is moved upwardly to seat against the upper O-ring 1118, thereby closing off the supply of pressurized fluid in the hollow handle 14 from the valve chamber 108 through the upper port or passage 114. At the same time, communication is established between the passages 106 and 122 through the valve chamber 108. The valve operator 124 is moved from the lower to the upper position described by a rEnual actuation of trigger 128, which is pivotally mounted at its rearward end on a downwardly projecting lug 130 formed on the underside of the handle 14 of the tool body. The forward end of the trigger 128 is connected to the lower end portion of the operator 124 below the body of the tool, and when the trigger is released air pressure from the passage 114 moves the ball valve 116 to seat on the lower O-ring 120.

The passage 122 below the valve chamber 108 is in communication with the feeder piston bore 78 by a passage 132 having its lower end in communication with the bore intermediate its ends. When the feeder piston 76 is in the position shown in FIG. 1 and the forward tip of the feed finger 88 is projecting into the drive track 34, the piston head 96 blocks the lower end of the passage 132 so that fluid cannot flow from the passage 122 into the feeder piston bore 78. However, when the feeder piston 76 is moved rearwardly to the position shown in FIG. 2, the lower end of the passage 132 is uncovered and fluid in the passage can flow into the bore 78 between the piston heads 94 and 96 of the piston member. An exhaust port 134 is provided in the lower wall of the feeder piston bore 78 at a position offset longitudinally of the lower end of the passage 132, and when the feeder piston 76 is moved to the rearward position, as shown in FIG. 2, the passage 132 and port 134 are in communication through the bore between the piston heads 94 and 96.

Digressing momentarily to the safety valve feature of the tool, the safety valve member 112 is slidable vertically in the bore 110 between a lower or safe position (FIG. 1) and an upper or fire position, as shown in FIG. 2. In order to actuate the safety valve in response to the movement ofthe tool into a firing position with the lower end of the nosepiece 36 pressed against a workpiece, a slidable foot or collar 136 is mounted for sliding movement on the lower end portion of the nosepiece around the lower end of the drive track 34. When the lower end of the nosepiece is out of engagement with a workpiece, as shown in FIGS. 1 and 3, the collar 136 is biased downwardly and extends below the lower end of the drive track 34, as shown in FIG. 1, and the biasing force is transmitted through a bracket member 138 connected between the collar and the lower end of the safety valve member 112. The safety valve member is formed with an annular ring or shoulder I40 adjacent its lower end, and a spring 142 engaging the ring urges the valve member and collar downwardly. The upper end of the spring 142 is seated against a shoulder formed by an enlarged, annular recess 144 in the tool body around the lower end of the safety valve passage 110. When the tool is ready for firing and the lower end of the nosepiece is pressed against a workpiece, as shown in FIG. 2, the collar 136 is moved upwardly on the lower end portion of the nosepiece, and the safety valve stem 112 is moved upwardly against the force of the spring 142 to the fire position of FIG. 2. The safety valve member 112 includes an upper end portion 112a having a sloping upper end face and an intermediate piston portion l12b spaced downwardly of the upper end portion and integrally connected thereto by a reduced diameter stern 112C. The valve member also includes a lower end or terminal portion 112d spaced downwardly of the intermediate and integrally connected thereto by a reduced diameter stem 112s. When the safety valve is in the lower or safe position, as shown in FIG. 1, the sloped upper surface of the upper end portion 112a permits communication directly between the reservoir 14 and the left-hand segment of the passage 106 extending between the valve bore 110 and the passage 104, and pressurized fluid is supplied to the valve chamber 54 above the valve flange 48, causing the poppet valve member 46 to close. Accordingly, when the safety valve stem 112 is in the safe position, firing of the tool cannot be initiated by movement of the trigger 128 because the upper end portion 112a of the safety valve member blocks the passage 106 intermediate its ends and thus prevents the fluid in the chamber 54 from being exhausted to the atmosphere. When the valve member 112 is moved to the upper or fire position, the upper end portion 112a is moved upwardly above the passage 106 and communication between opposite end portions of this passage is established through the safety valve bore 110 around the narrow stern portion 112c. When the trigger 128 is squeezed, unseating the ball valve 116 from its lower seat 120 in the valve chamber 108, communication is established between the poppet valve chamber 54 and the lower end of the passage 132 which terminates in the feeder piston bore 78. However, the tool still cannot be fired in this condition until the feeder piston 76 is moved rearwardly to the position of FIG. 2, thereby withdrawing the pawl or finger 88 from the drive track so that the driver 32 on its downward power stroke will not engage the finger, thereby damaging the tool.

In accordance with the present invention, positive means are provided for insuring that the finger 88 is retracted from the drive track before a downward power stroke of the driver 32 can commence. In order to move the feeder piston assembly 76 on a rearward stroke, thereby withdrawing the tip of the finger 88 from the drive track and enabling the tool to be fired, a passage 146 is provided in communication at its upper end with the passage 58 and in communication at its lower end with the safety valve bore 110 at a point spaced below the passage 106. When the safety valve member 112 is in the lower safe position, as shown in FIG. 1, the intermediate body portion 112!) blocks off the lower end of the passage 146, and when the valve member is then moved to the upper or fire position, the intermediate portion 1I2b moves upwardly above the lower end of the passage 146 and permits a flow of compressed air into the safety valve bore 110 around the stem portion l12e. This compressed fluid flows around the stem portion 112e and into the forward end of the feeder piston bore 78 through a feeder passage 148, having its upper end in communication with the safety valve bore 110 at a point beneath the lower end ofthe passage 146, and the lower end of the passage 148 is in axial communication with the forward or closed end of the feeder piston bore 78. As the valve stem 112 is moved upwardly from the safe to the fire position, compressed fluid from the reservoir 14 flows into the forward end of the feeder piston chamber 78 via the passages 58 and 146, around the stem portion I12e of the safety valve 112, through the passage 148 communicating between the safety valve bore 110 and into the forward end of the feeder piston bore 78. This fluid drives the feeder piston 76 rearwardly to the position of FIG. 2 against the biasing spring 98 and, as described, retracts the finger 88 clear ofthe drive track 34. As this occurs, the piston head 96 uncovers the exhaust port 134 and the lower end of the passage 132 which communicates with the bore, thereby establishing an exhaust path between the passage and the atmosphere between the piston heads 94 and 96. When the trigger 128 is now squeezed, a power stroke is initiated by the exhausting of pressurized fluid from the valve chamber 54 through passages 42a, 100, conduit 102, passages 104, 110 and 106, valve chamber 108, passages I22 and 132, feeder piston bore 78 between the piston heads 94 and 96, and finally the exhaust port 134. After the firing stroke has been completed and the lower piston head 20 strikes the cushion member 56 at the lower end of the cylinder bore 18, when either the safety valve 112 or the trigger 128 is released, compressed air is again supplied to the upper poppet valve chamber 54, causing the poppet valve 46 to close, sealing the upper end of the cylinder insert 30. When this occurs, the piston member 22 commences an upward return stroke, as previously described.

After a power stroke, when the safety valve 112 is moved from the fire position to the safe position, the intermediate portion 1l2b moves downwardly, closing the lower end of the passage 146, and the lower end portion 122d uncovers the upper end of an exhaust passage 150 which has a lower end in communication with the atmosphere. The compressed fluid in the forward end of the feeder piston bore 78 is then free to escape to the atmosphere through the passage I48, around the stem portion 112:: in the valve bore 110, and out the exhaust passage 150. When this occurs, the biasing spring 98 at the 9- rearward end of the feeder piston bore 78 moves the piston assembly 76 forwardly on a feeding stroke, thereby advancing another nail 60 into a centered position in the drive track ready to be driven. The cycle of operation is then repeated as described, until all of the nails in the magazine have been driven.

As previously mentioned, forward movement of the feeder piston 76 is restricted by engagement of the forward tip of the pawl or finger 88 with the shank of the nail centered in the drive track 34. However, if a nail is not present in the drive track, the feeder piston 76 is free to move farther forward to the full forward position, as shown in FIG. 3, until the piston is stopped by engagement of a resilient O-ring 152 on the forward end of the piston against the frustoconical surface of an annular recess 154. The annular recess 154 is formed at the lower end of the passage 148 at the forward end of the feeder piston bore 78 and is mounted on a short projection ahead of the piston head 94 for seating in the recess 154 to close communication between the forward end of the bore 78 and the passage 148. If the safety valve member 112 is now moved from the safe to the fire position, thereby supplying pressurized fluid to the passage 148, none of this fluid can reach the forward end of the feeder piston bore 78 to move the feeder piston 76 rearwardly and, hence, the exhaust port 134 mains covered by the piston head 96 and the tool cannot be fired, regardless of the position of safety valve member 112 or movement of the trigger 128 because the recess 154 has a reduced diameter which is not great enough to permit air pressure force on the piston to overcome the spring 98. Thus, after the last nail has been driven the tool cannot be fired, and this feature prevents damage to the tool and advises the operator to reload if he is not already aware that the nail supply has been exhausted.

From the foregoing, it will be seen that the tool of the present invention automatically prevents firing of the tool when there are no more nails in the magazine 64. In addition, the tool includes means for positively feeding the nails into the drive track in synchronism with the movements of the driver and the nails are guided into the drive track by the forward tip of the finger 88. The tool cannot be fired until the feedpawl 88 is positively retracted from the drive track regardless of the position of the safety valve or trigger.

After the last nail in the tool has been fired and the feeder piston 76 is in the inoperative or full forward position, as

' shown in FIG. 3, the feeder piston is retracted rearwardly by manually grasping the knob 82 and moving it rearwardly until the forward finger 88 is clear of the guideway between the safety valve 112 from the safe to the fire position and manual squeezing of the trigger 128. It is also possible to operate the tool on continuously repeating cycles' by maintaining the trigger in a depressed position and moving the lower end of the nosepiece into and out of contact with the workpiece to thereby initiate power strokes of the driver.

In accordance with the present invention, in FIGS. 4 through 6 is illustrated another embodiment of the fastener driving tool referred to generally by the reference numeral 200, and differing generally from the previous embodiment of FIGS. 1 through 3a in that it is not necessary to recycle the safety valve in order to initiate each cycle of operation of the tool including a power and return stroke of the driver 32. Components of the tool 200, which are identical to or substantially similar to the components of thetool 10 of the previously described embodiment are given identical reference nurnerals and will not be described in detail hereinafter except to the extent necessary in order to relate'to the features of the second illustrated embodiment of the invention.

In the tool 200, the tubular conduit 102 leading to the poppet valve chamber 54 above the flange portion 48 of the pop pet valve assembly 46 is connected to a valve chamber 202 having a spherical ball valve member 204 mounted therein for movement between an upper and lower position. The tubular conduit 102 is connected into a sidewall portion of the valve chamber 202 through a short drilled passageway 206, and the upper end of the valve chamber is in communication with the reservoir 14 in the tool handle via a short passage or port 200. An O-ring 210 is provided around the port opening 208 so that when the ball valve member 204 is forced upwardly t0 the position of FIG. 5, the passage 208 is closed and communication between the valve chamber 202 and the pressurized fluid in the handle portion 14 is cut off. The lower end of the valve chamber 202 is in communication with a drilled passage 212 and an O-ring 2141 is provided at the lower end of the chamber 202 so that when the ball valve member 204 is in a downward position, as shown in FIGS. 4 and 6, air pressure from the handle reservoir 14 forces the valve member 204 tightly against the O-ring 214 closing off communication between the valve chamber 202 and the upper end of the passage 212. lm mediately below the valve chamber 202, the passage 212 is in communication with an exhaust passage 216 opening to the atmosphere so that when the valve member 20d is seated against the upper O-ring 210, the conduit 102 leading to the poppet valve chamber can exhaust to the atmosphere through the valve chamber 202, passage 206, upper end of the bore 212 and passage 216 to initiate a firing stroke of the tool. The lower end of the passage 212 is in communication with a larger diameter cylinder or bore 218 formed in the body of the tool. Within the coaxially aligned passage 212 and cylinder 218 is mounted for sliding movement a movable piston member 220 including an elongated piston rod 222 having an upper portion slidable in the passage 212. At the upper end of the piston rod 222 is provided a short, ball valve actuator or projection 224 of reduced diameter andadapted to move upwardly to unseat the ball valve member 204 from the O-ring 214 and force it upwardly to seat against the upper O-ring 210 and seal off the port 208.

The piston member 220 includes an upper piston 226 spaced below the projection 224 and slidable in the large diameter bore or cylinder 218 from an intermediate position shown in FIG. 4 to an upper position shown in FIG. 5, where it bears against an annular surface at the upper end of the cylinder 218. When the piston member 220 is in the upper position, the actuator projection 224 engages the ball valve 204, lifting it off the lower O-ring 214 and moving it upwardly to seat against the upper O-ring 210, thus permitting the pressurized fluid in the poppet valve chamber 54 to exhaust into the atmosphere and thereby initiate a power stroke of the piston assembly 22 and driver 32 to drive a fastener downwardly in the drive track 34. The piston member 220 also includes a smaller diameter lower piston 228 spaced below the piston 226 and slidable within a tubular sleeve 230 inserted into the lower portion of the cylinder 218 adjacent the exhaust end. When the piston member 220 is in the intermediate or upper position, the lower piston 228 seals off the lower end of the cylinder 218 by tightly sealed engagement around the internal surface or bore of the insert 230 and normally prevents the exhaust of fluid in the cylinder 2118 contained between the upper and lower piston members 226 and 228, respectively.

The lower end of the piston rod 222 is pivotally connected to a triangularly-shaped magazine actuating member 232 by means of a cross-pin 234 which is slidably disposed in a slot 232a at the rearward, upper corner of the actuator. The forward, upper corner of the magazine actuator is mounted for pivotal movement relative to the magazine 64 on a mounting pin 236, extending laterally transversely of the longitudinal axis of the magazine. The lower corner of the triangularlyshaped magazine actuator is pivotally interconnected with the magazine feeder member 84 by a pin 238 which projects through an elongated slot 240a formed in a magazine cocking llll member 240 which is also pivotally mounted on the pin 236. The cocking member 240 includes a knob or handle 241 at the lower end manually movable by a tool operator to cock the magazine member and retract the feed pawl or finger 88 from the drive track after the last nail has been driven and a new supply or strip of nails 60 is being inserted into the magazine. When the piston member 220 is in the intermediate position shown in FIG. 4, the forward end or tip 88 of the feeding finger or pawl is in contact with the leading fastener 60 in the magazine which is in centered position in the drive track 34 ready to be driven by a power stroke of the driver 32. When a power stroke is initiated by movement of the piston 220 from the position of FIG. 4 to the upper position of FIG. 5, the feeder pawl or finger 88 is retracted rearwardly out of the drive track, as in the prior embodiment, so that no interference between the driver 32 and the feed pawl can occur.

Similar to the tool 10 of the previous embodiment, the tool 200 includes a safety valve mechanism which is operatively interconnected with presser foot 136 and connecting bracket 138 forming a touch trip mechanism for the tool. The upper end of the bracket 138 is connected to the lower end of a safety valve rod 242 which is slidable in an elongated bore 244, having its upper end in communication with the interior of the handle reservoir 14 and a lower end open to the atmosphere. The safety valve rod 242 is biased downward by the compression spring 142 which is seated in an enlargement 244a at the lower end of the safety valve bore 244, and the lower end of the spring 142 bears downwardly against an annular collar 140 provided on the lower end portion of the valve rod. The presser foot 136 is thus biased downwardly to the safe position below the lower end of the drive track 34 by the spring 142. When the tool is to be fired and the lower end of the drive track 34 is pressed against the workpiece, the presser foot 136 is moved upwardly to the fire position and the valve rod 242 is moved upwardly from the safe position of FIGS. 4 and 6 to the fire position of FIG. 5. The safety valve rod includes a sloped upper end surface 242a and an annular recess 24212 in the body of the rod spaced downwardly from the upper end surface. The safety valve passage 244 is in communication with the upper end surface of the cylinder 218 above the piston 226 by a cross passage 246.

When the safety valve rod 242 is in the lower or safe position, shown in FIG. 4, the sloped upper end surface 242a permits fluid to flow from the reservoir 14 into the upper end of the bore 244 and through the passage 246 into the upper end of the cylinder 218 above the piston portion 226, moving the piston 220 downwardly from the position of FIG. to the position of FIG. 4. Movement of the piston 220 in the above manner, causes a new fastener 60 to be fed into the drive track 34 and further downward movement of the piston member 220 is limited because of engagement of the forward end of the feed pawl or finger 88 with the shank of the fastener when it is centered in the drive track 34. When the safety valve member 242 is in the downward or safe position, pressurized air from the handle reservoir 14 is continuously supplied to the upper end of the cylinder 218 above the piston member 226 and prevents upward movement of the piston member 220 from the position of FIG. 4 to that of FIG. 5 and, accordingly, the valve member 204 is seated on the lower O-ring 214 and a drive stroke of the piston assembly 22 and driver 32 cannot be initiated. When the tool 208 is moved into working position and the presser foot 13-6 is depressed upwardly by engagement against a workpiece, the safety valve rod 242 is moved upwardly to the fire position, and the annular recess 242i) is aligned with the passage 246 and a short intermediate passageway 248 which extends into the sidewall of a trigger valve chamber 108 similar to the trigger valve chamber in the preceding embodiment.

Within the trigger valve chamber 108 is mounted a ball valve member 116 and the upper end of the valve chamber is connected to the interior of the handle reservoir 14 through a port 114 which is surrounded by an upper O-ring 118 having an upper valve seat. The lower end of the trigger valve chamber 108 is in communication with the atmosphere through a downwardly extending port or passage 122 and a lower O-ring seat is provided in the valve chamber to seal off the passage 122 when the ball valve is seated thereon, as in FIGS. 4 and 6. The ball valve 116 is mounted for movement within the chamber 108 between a lower position seated against the lower O-ring 120 and closing off the passage 122, and is movable upwardly to a seated position against the O- ring 118 sealing off the port 114 by means of an actuator pin 126, having a diameter smaller than the passage 122 and pivotally connected to the forward end of a trigger 128. On upward depression of the trigger 128, the stem 126 forces the ball valve member 116 upwardly, closing off the port 114 to the reservoir 14 and the short transverse passage 248 then permits air in the upper end portion of the cylinder 218 above the piston 226 to exhaust to the atmosphere through the passage 246, recess 24% on the safety valve rod 242, passage 248, valve chambers 108, and passage 122 around the stern 126. When this occurs, the piston member 220 moves upwardly because of the pressurized fluid in the cylinder 218 between the pistons 226 and 228, and this movement retracts the magazine feeder pawl 88 from the drive track 34 and unseats the ball valve 204 from the lower O-ring seat 214, thereby permitting a drive stroke of the piston assembly 22 and driver 32 to be initiated as the fluid from the poppet valve 54 exhausts to the atmosphere through the passage 216. It is thus seen that a power or driving stroke cannot be commenced until the forward end of the magazine feed pawl or finger 88 has been positively retracted from the drive track 34 to be clear of the driver 32. After a power stroke has been completed and either the safety valve 242 is released to return to the downward or safe position or the trigger 128 is released allowing the trigger valve 116 to reseat on the lower O-ring 120, pressurized fluid is again introduced into the upper end of the cylinder 218 above the piston 226 via the safety valve passage 244 and passage 246 or via the port 114, valve chamber 108, passage 248, annular recess 242b and passage 246. When this occurs, the piston 220 moves downwardly to the position of FIG. 4, and thereby advances another fastener or nail 60 into a centered position in the drive track ready to be driven. As previously stated, engagement between the forward end of the pawl or finger 88 and the shank of the leading nail 60 in the drive track prevents further downward movement of the piston member 220 beyond the intermediate position of FIG. 4. The tool can again be fired if the safety valve rod 242 is still in the upper or fire position and the trigger 128 is in the upper or fire position unseating the trigger valve ball 116, as previously described. Successive operative cycles may be initiated by continuously maintaining either the trigger 128 or the safety valve rod 242 in the upper or fire position and cycling the other one of the two between the fire and safe positions.

When the last nail or fastener 60 in the magazine 64 has been driven, the forward end of the feed pawl or finger 88 is moved by the piston member 220 to a full forward position, as shown in FIG. 6 wherein the forward end of the pawl bears against the forward wall of the drive track 34. This occurs because the fluid pressure in the upper end of the cylinder 218 bearing downwardly on the piston 226, forces the piston rod assembly 220 downwardly from the position of FIG. 5 to the position of FIG. 6, wherein the lower piston 228 is moved below a tapered lower bore portion of the sleeve insert 230 and exhausts the fluid from the cylinder 218 between the pistons 226 and 228. When the pressure between the piston portions 226 and 228 is relieved and exhausted to the atmosphere, there is no upward force acting on the piston member 220 to unseat the valve 204 from its lower seat 214, and subsequent depression of the trigger 128 and safety valve member 242 is ineffective to initiate a firing stroke ofthe tool. The tool 280 cannot be fired after the last nail 60 has been driven, and this feature prevents an inadvertent power stroke of the driver when there are no fasteners present in the tool magazine and eliminates damage to the tool, resulting from initiating a power stroke when the tool is empty.

In order to reload the tool, a new supply of fasteners 60 is inserted into the magazine 64 and is advanced forwardly until the leading nail 60 is adjacent the entrance to the drive track. The knob 241 on the cocking lever 240 is manually retracted rearwardly, causing the lever to pivot counterclockwise. This movement forces the piston rod member 220 upwardly, and the lower piston 228 again is sealed in the insert sleeve 230. When the piston 228 is moved into sealing engagement with the sleeve insert 230, the upper piston 226 is spaced above the sleeve insert and compressed fluid from the handle reservoir 14 flows into the cylinder 218 between the pistons 226 and 228 through a passage 250. With pressurized fluid present in the cylinder 218 between the pistons 226 and 228, a power stroke can again be initiated by exhausting the fluid from the upper end of the cylinder 218 above the piston 226, as previously described.

ln order to prevent an inadvertent firing stroke of the piston assembly 22 and driver 32 when the tool is cocked by manual movement of the cocking lever 240, as described, a stop lug 252 is provided on an adjacent sidewall of the magazine for limiting the pivotal movement of the lever during a cocking operation so that the piston member 220 does not move upwardly beyond the intermediate position of FIG. 4 to the firing position of FIG. 5. After the tool is loaded with a new supply of fasteners and is cocked as described, firing strokes can again be initiated by depression of the safety valve rod 242 and trigger 128, as previously described.

From the foregoing, it will be seen that an embodiment of the invention illustrated in FIGS. 4 through 6 provides positive means for retracting the feeder pawl 88 from the drive track 34 before a power stroke of the driver 32 can be initiated. Furthermore, the tool 200 can again be recycled for successive firing strokes while holding the nosepiece in constant contact against the workpiece and cycling the trigger 122. Or in the alternative, the trigger 128 can be maintained in a depressed condition and the tool can be cycled by moving the presser foot 136 against and away from the workpiece. The tool 200 also includes a last nail feature which prevents firing of the tool after the last nail magazine has been exhausted and, once exhausted, the new fasteners can be loaded into the magazine and the tool is manually cocked with the cocking lever 240, putting it in a ready condition for commencement of subsequent firing operations. y}

in the tool 10, illustrated in FIGS. 1-3, it is necessary to cycle the safety valve stem [12 in order to feed each new nail into the drive track. In the tool 200 of FIGS. 4-6, it is not necessary to cycle the safety valve 242 to feed the nails into the drive track. it has been found in some instances that too] operators using tools of the latter type have taped or otherwise permanently secured the valve rod 242 in the fire position, thus enabling the tool to be manipulated and fired somewhat easier and at a slightly higher rate than possible otherwise. This, of course, eliminates the safety feature afforded by the valve 242 and results in a dangerous situation in that the tool can be fired in any position by squeezing the trigger regardless of whether or not the lower end'of the nosepiece is pressed against a workpiece. In the tool 10, however, the safety valve feature cannot be disabled by taping or otherwise securing the valve stem 112 in the fire position because it is necessary to cycle the safety valve to feed each new nail into the drive track. The tool cannot remain operative if the safety valve is taped or restrained in the fire position and, as a result, the tool is operative only in the safe manner as intended. When restraining of the safety valve is not a serious problem, the tool 200 offers the advantage of not requiring the cycling of the safety valve each time a nail is to be driven.

Although the present invention has been described with reference to two illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention.

We claim:

1. A fastener driving too] comprising a drive track for guiding fasteners as *they are driven, a pneumatically powered driver in said drive track movable on a power stroke to drive fasteners and a return stroke, pusher means for feeding fasteners into said drive track and movable between a forward position extending into said drive track and a rearward position rearwardly retracted therefrom, and fluid control means including a piston slidable in a cylinder, said piston interconnected with said pusher means for moving the same and providing valving action for preventing the initiation of a power stroke of said driver-until said pusher means is retracted from said drive track.

2. The driving too] of claim 1 wherein said control means includes first motor means for moving said driver on a power and return stroke and second motor means for moving said pusher means, and passage means operably interconnecting said first and second motor means whereby said second motor means normally closes said passage means preventing a power stroke of said driver until said pusher means is clear of said drive track.

3. The driving tool of claim 2 including safety valve means responsive to the position of said drive track relative to a workpiece movable between a safe anda fire position and operable upon movement from said safe to said fire position to retract said pusher means from said drive track, said safety valve means operable to activate said second motor means to feed a fastener into said drive track with said pusher means when returned from said fire position to said safe position.

4. The driving tool of claim 2, wherein said control means comprises a manual trigger valve operable to open and close said passage means between said first and second motor means.

5. The driving tool of claim 3 wherein said second motor means includes valve means operable to open communication between one end of said passage means and the atmosphere when said safety valve means is moved from the safe to the fire position.

6. The driving tool of claim 5 wherein said valve means on said second motor means is operable to close communication between said one end of said passage means and the atmosphere when said safety valve means is returned from the fire to the safe position.

7. A fastener driving tool comprising a drive track, a driver slidable in said drive track, pneumatic motor means operable to move said driver on a power and return stroke in said drive track, pusher means operable to move into and out of said drive track to position fasteners therein to be driven, control valve means for activating said motor means to initiate a power stroke of said driver, means for retracting said pusher including a piston slidably mounted in a cylinder and a valve, said piston operable to actuate said valve for preventing a power stroke of said driver until said pusher means is retracted from said drive track.

8. The driving tool of claim 7 wherein said control valve means includes exhaust passage means in communication between said motor means and the atmosphere for initiating a power stroke, said retracting means normally closing said passage means and operable to open said passage means after retraction of said pusher means from said drive track.

9. The driving too] of claim 8 wherein said retracting means is operable to advance said pusher means into said drive track after said motor means has initiated a return stroke of said driver. v

10. A fastener driving tool comprising a drive track for receiving fasteners, a driver slidable in said drive track and movable on a power stroke to drive fasteners and a return stroke in an opposite direction, pusher means movable on a feed stroke from a retracted position clear of said drive track forwardly to a forward position extending into said drive track and movable rearwardly on a return stroke in the opposite direction to said retracted position, first valve means for initiating a power stroke of said driver and second valve means associated therewith preventing the initiation of a power stroke until said pusher means moves on a return stroke to said retracted position.

11. The driving tool of claim wherein said second valve means comprises piston means slidable in a bore, and said first valve means includes passage means intersecting said bore and blocked by said piston means when said pusher means is in said forward position.

12. The driving tool of claim 11 wherein said piston means moves to open communication between said passage means and said bore when said pusher means is moved to said retracted position.

13. The tool of claim 12 including safety valve means movable between a safe and a fire position, and means controlled by said safety valve means to supply pressurized fluid to move said piston means to retract said pusher means when said safety valve means is moved from said safe to said fire position.

14. The driving tool of claim 10 wherein said first valve means includes passage means and a pair of valve members in series communication in said passage means, each valve member movable between a first and second position and operable to initiate a power stroke of said driver only when both valve members are moved to said second position.

15. The driving tool of claim 10 wherein said second valve means includes a piston member interconnected with said pusher means and a second valve member, said first valve means including a valve member operable between a first and second position to move said piston member to retract and advance respectively said pusher means.

16. The driving tool of claim 15 wherein said piston member is operable to open and close said second valve member upon retraction and advancement of said pusher means, said second valve member opening to initiate a power stroke of said driver and said one valve member operable to initiate a return stroke thereof.

17. The driving tool of claim 16 wherein said piston member is movable to a third position in response to the absence of fasteners in said tool to close said second valve member and prevent the initiation of a power stroke of said driver.

18. The driving tool of claim 17 wherein said first valve means includes a first valve passage between said piston member and a pair of valves in series movable between open and closed positions to connect and disconnect an end of said first valve passage to the atmosphere.

19. A fastener driving tool comprising a drive track and a driver slidably disposed therein,'motor means for reciprocating said driver to drive successive fasteners positioned in said drive track, safety valve means movable on an operating cycle between a safe and a fire position and operably connected with said motor means to prevent initiation of a drive stroke of said driver until said safety valve means has been cycled between said safe and fire positions, said safety valve means including a workpiece engaging structure movably mounted adjacent the lower end of said drive track for movement between a safe position projecting below said lower end of said drive track and a fire position spaced upwardly thereof, and reciprocating feeder means for advancing successive fasteners into said drive track and means operatively interconnecting said feeder means and said safety valve means for initiating a feeding stroke of said feeder means in response to cycling of said safety valve means between said safe and fire positions.

20. The fastener driving tool of claim 1 wherein said cylinder is formed with a port therein for cooperation with said piston to provide said valving action upon movement of said piston to open and close said port.

21. The fastener driving tool of claim 1 wherein said piston includes a pair of piston portions having different diameters, at least one of said piston portions serving as a component for said valving action.

22. The fastener driving tool of claim 20 wherein said piston includes an axial stem of reduced diameter between said piston portions forming a piston chamber movable into and out of communication with said port.

23. The fastener driving tool of claim 7 wherein said valve includes a port formed in said cylinder and opened and closed by said piston.

24. The fastener driving tool of claim 23 wherein said piston includes portions of different diameters, at least one portion functioning as a component of said valve for controlling the operation of said motor means for initiating a power stroke of said driver. 

1. A fastener driving tool comprising a drive track for guiding fasteners as they are driven, a pneumatically powered driver in said drive track movable on a power stroke to drive fasteners and a return stroke, pusher means for feeding fasteners into said drive track and movable between a forward position extending into said drive track and a rearward position rearwardly retracted therefrom, and fluid control means including a piston slidable in a cylinder, said piston interconnected with said pusher means for moving the same and providing valving action for preventing the initiation of a power stroke of said driver until said pusher means is retracted from said drive track.
 2. The driving tool of claim 1 wherein said control means includes first motor means for moving said driver on a power and return stroke and second motor means for moving said pusher means, and passage means operably interconnecting said first and second motor means whereby said second motor means normally closes said passage means preventing a power stroke of said driver until said pusher means is clear of said drive track.
 3. The driving tool of claim 2 including safety valve means responsive to the position of said drive track relative to a workpiece movable between a safe and a fire position and operable upon movement from said safe to said fire position to retract said pusher means from said drive track, said safety valve means operable to activate said second motor means to feed a fastener into said drive track with said pusher means when returned from said fire position to said safe position.
 4. The driving tool of claim 2 wherein said control means comprises a manual trigger valve operable to open and close said passage means between said first and second motor means.
 5. The driving tool of claim 3 wherein said second motor means includes valve means operable to open communication between one end of said passage means and the atmosphere when said safety valve means is moved from the safe to the fire position.
 6. The driving tool of claim 5 wherein said valve means on said second motor means is operable to close communication between said one end of said passage means and the atmosphere when said safety valve means is returned from the fire to the safe position.
 7. A fastener driving tool comprising a drive track, a driver slidable in said drive track, pneumatic motor means operable to move said driver on a power and return stroke in said drive track, pusher means operable to move into and out of said drive track to position fasteners therein to be driven, control valve means for activating said motor means to initiate a power stroke of said driver, means for retracting said pusher including a piston slidably mounted in a cylinder and a valve, said piston operable to actuate said valve for preventing a power stroke of said driver until said pusher means is rEtracted from said drive track.
 8. The driving tool of claim 7 wherein said control valve means includes exhaust passage means in communication between said motor means and the atmosphere for initiating a power stroke, said retracting means normally closing said passage means and operable to open said passage means after retraction of said pusher means from said drive track.
 9. The driving tool of claim 8 wherein said retracting means is operable to advance said pusher means into said drive track after said motor means has initiated a return stroke of said driver.
 10. A fastener driving tool comprising a drive track for receiving fasteners, a driver slidable in said drive track and movable on a power stroke to drive fasteners and a return stroke in an opposite direction, pusher means movable on a feed stroke from a retracted position clear of said drive track forwardly to a forward position extending into said drive track and movable rearwardly on a return stroke in the opposite direction to said retracted position, first valve means for initiating a power stroke of said driver and second valve means associated therewith preventing the initiation of a power stroke until said pusher means moves on a return stroke to said retracted position.
 11. The driving tool of claim 10 wherein said second valve means comprises piston means slidable in a bore, and said first valve means includes passage means intersecting said bore and blocked by said piston means when said pusher means is in said forward position.
 12. The driving tool of claim 11 wherein said piston means moves to open communication between said passage means and said bore when said pusher means is moved to said retracted position.
 13. The tool of claim 12 including safety valve means movable between a safe and a fire position, and means controlled by said safety valve means to supply pressurized fluid to move said piston means to retract said pusher means when said safety valve means is moved from said safe to said fire position.
 14. The driving tool of claim 10 wherein said first valve means includes passage means and a pair of valve members in series communication in said passage means, each valve member movable between a first and second position and operable to initiate a power stroke of said driver only when both valve members are moved to said second position.
 15. The driving tool of claim 10 wherein said second valve means includes a piston member interconnected with said pusher means and a second valve member, said first valve means including a valve member operable between a first and second position to move said piston member to retract and advance respectively said pusher means.
 16. The driving tool of claim 15 wherein said piston member is operable to open and close said second valve member upon retraction and advancement of said pusher means, said second valve member opening to initiate a power stroke of said driver and said one valve member operable to initiate a return stroke thereof.
 17. The driving tool of claim 16 wherein said piston member is movable to a third position in response to the absence of fasteners in said tool to close said second valve member and prevent the initiation of a power stroke of said driver.
 18. The driving tool of claim 17 wherein said first valve means includes a first valve passage between said piston member and a pair of valves in series movable between open and closed positions to connect and disconnect an end of said first valve passage to the atmosphere.
 19. A fastener driving tool comprising a drive track and a driver slidably disposed therein, motor means for reciprocating said driver to drive successive fasteners positioned in said drive track, safety valve means movable on an operating cycle between a safe and a fire position and operably connected with said motor means to prevent initiation of a drive stroke of said driver until said safety valve means has been cycled between said safe and fire positions, said safety valve means inCluding a workpiece engaging structure movably mounted adjacent the lower end of said drive track for movement between a safe position projecting below said lower end of said drive track and a fire position spaced upwardly thereof, and reciprocating feeder means for advancing successive fasteners into said drive track and means operatively interconnecting said feeder means and said safety valve means for initiating a feeding stroke of said feeder means in response to cycling of said safety valve means between said safe and fire positions.
 20. The fastener driving tool of claim 1 wherein said cylinder is formed with a port therein for cooperation with said piston to provide said valving action upon movement of said piston to open and close said port.
 21. The fastener driving tool of claim 1 wherein said piston includes a pair of piston portions having different diameters, at least one of said piston portions serving as a component for said valving action.
 22. The fastener driving tool of claim 20 wherein said piston includes an axial stem of reduced diameter between said piston portions forming a piston chamber movable into and out of communication with said port.
 23. The fastener driving tool of claim 7 wherein said valve includes a port formed in said cylinder and opened and closed by said piston.
 24. The fastener driving tool of claim 23 wherein said piston includes portions of different diameters, at least one portion functioning as a component of said valve for controlling the operation of said motor means for initiating a power stroke of said driver. 